Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

Comparative information of the Company’s overall revenues (in millions) by global and geographical markets for the fiscal years ended December 31, 2020, 2019 and 2018 were as follows:

(in millions)	2020						2019						2018
	HPMC		AA&S		Total		HPMC		AA&S		Total		HPMC		AA&S		Total
Diversified Global Markets:
Aerospace & Defense	$	946.9	$	413.1	$	1,360.0	$	1,624.1	$	506.3	$	2,130.4	$	1,562.9	$	402.6	$	1,965.5
Energy*	106.2		512.7		618.9		153.6		643.3		796.9		133.9		646.8		780.7
Automotive	5.5		257.7		263.2		10.5		286.1		296.6		9.5		313.9		323.4
Electronics	0.9		176.8		177.7		0.5		162.7		163.2		1.5		155.4		156.9
Food Equipment & Appliances	—		159.2		159.2		0.3		205.5		205.8		0.4		244.5		244.9
Construction/Mining	18.6		123.4		142.0		42.5		152.5		195.0		72.7		153.3		226.0
Medical	47.7		71.4		119.1		85.4		87.0		172.4		106.0		77.1		183.1
Other	38.8		103.2		142.0		61.6		100.6		162.2		76.2		89.9		166.1
Total	$	1,164.6	$	1,817.5	$	2,982.1	$	1,978.5	$	2,144.0	$	4,122.5	$	1,963.1	$	2,083.5	$	4,046.6

*Includes the oil & gas, downstream processing, and specialty energy markets.

(in millions)	2020						2019						2018
	HPMC		AA&S		Total		HPMC		AA&S		Total		HPMC		AA&S		Total
Primary Geographical Market:
United States	$	641.0	$	1,168.1	$	1,809.1	$	1,042.6	$	1,412.0	$	2,454.6	$	983.6	$	1,364.5	$	2,348.1
China	31.0		284.5		315.5		93.9		261.7		355.6		71.2		248.8		320.0
United Kingdom	101.9		24.6		126.5		156.7		17.1		173.8		225.6		16.5		242.1
Germany	76.6		48.8		125.4		147.2		72.1		219.3		159.0		88.2		247.2
Japan	44.7		41.5		86.2		95.0		52.7		147.7		128.1		86.8		214.9
France	66.6		18.4		85.0		132.7		22.8		155.5		146.3		37.3		183.6
Rest of World	202.8		231.6		434.4		310.4		305.6		616.0		249.3		241.4		490.7
Total	$	1,164.6	$	1,817.5	$	2,982.1	$	1,978.5	$	2,144.0	$	4,122.5	$	1,963.1	$	2,083.5	$	4,046.6

Comparative information of the Company’s major high-value and standard products based on their percentages of sales is included in the following table. In conjunction with the Company’s announced ongoing exit of standard stainless products, ATI reclassified certain items as High-Value Products within AA&S segment results. Prior period information reflects these reclassifications. HRPF conversion service sales in the AA&S segment are excluded from this presentation.

	2020						2019						2018
	HPMC		AA&S		Total		HPMC		AA&S		Total		HPMC		AA&S		Total
Diversified Products:
High-Value Products
Nickel-based alloys and specialty alloys	38	%	29	%	33	%	38	%	33	%	35	%	37	%	31	%	33	%
Titanium and titanium-based alloys	28	%	11	%	17	%	26	%	11	%	18	%	23	%	10	%	17	%
PRS products	—	%	25	%	15	%	—	%	23	%	12	%	—	%	23	%	12	%
Precision forgings, castings and components	34	%	—	%	14	%	36	%	—	%	18	%	40	%	—	%	20	%
Zirconium and related alloys	—	%	15	%	9	%	—	%	11	%	6	%	—	%	11	%	5	%
Total High-Value Products	100	%	80	%	88	%	100	%	78	%	89	%	100	%	75	%	87	%
Standard Products
Standard stainless products	—	%	20	%	12	%	—	%	22	%	11	%	—	%	25	%	13	%
Total	100	%	100	%	100	%	100	%	100	%	100	%	100	%	100	%	100	%

Schedule of Accounts Receivable - Reserve for Doubtful Accounts

The following represents the rollforward of accounts receivable - reserve for doubtful accounts for the fiscal years ended December 31, 2020, 2019 and 2018:

(in millions)
Accounts Receivable - Reserve for Doubtful Accounts
Balance as of December 31, 2017	$	5.9
Expense to increase the reserve	1.9
Write-off of uncollectible accounts	(1.8)
Balance as of December 31, 2018	6.0
Expense to increase the reserve	0.2
Write-off of uncollectible accounts	(1.6)
Balance as of December 31, 2019	4.6
Expense to increase the reserve	0.2
Write-off of uncollectible accounts	(0.5)
Balance as of December 31, 2020	$	4.3

Schedule of Contract Assets and Liabilities

The following represents the rollforward of contract assets and liabilities for the fiscal years ended December 31, 2020, 2019 and 2018:

(in millions)
Contract Assets
Short-term	2020		2019		2018
Balance as of beginning of fiscal year	$	38.5	$	51.2	$	36.5
Recognized in current year	84.2		74.5		92.9
Reclassified to accounts receivable	(83.9)		(79.9)		(95.8)
Impairment	—		—		—
Reclassification to/from long-term	0.1		—		16.8
Divestiture	—		(7.3)		—
Other	—		—		0.8
Balance as of period end	$	38.9	$	38.5	$	51.2
Long-term	2020		2019		2018
Balance as of beginning of fiscal year	$	0.1	$	0.1	$	16.9
Recognized in current year	—		—		—
Reclassified to accounts receivable	—		—		—
Impairment	—		—		—
Reclassification to/from short-term	(0.1)		—		(16.8)
Balance as of period end	$	—	$	0.1	$	0.1

(in millions)
Contract Liabilities
Short-term	2020		2019		2018
Balance as of beginning of fiscal year	$	78.7	$	71.4	$	69.7
Recognized in current year	170.3		126.1		76.7
Amounts in beginning balance reclassified to revenue	(54.9)		(49.2)		(49.6)
Current year amounts reclassified to revenue	(90.1)		(76.0)		(42.7)
Other	—		1.9		2.7
Reclassification to/from long-term	7.8		4.5		14.6
Balance as of period end	$	111.8	$	78.7	$	71.4
Long-term	2020		2019		2018
Balance as of beginning of fiscal year	$	25.9	$	7.3	$	22.2
Recognized in current year	14.9		24.2		0.7
Amounts in beginning balance reclassified to revenue	(1.0)		(1.1)		(1.0)
Current year amounts reclassified to revenue	—		—		—
Other	—		—		—
Reclassification to/from short-term	(7.8)		(4.5)		(14.6)
Balance as of period end	$	32.0	$	25.9	$	7.3